Amnesty International is urging the United Nations to help eliminate restrictions by authoritarian governments on Internet access, saying such repression violates basic human rights.

An Amnesty delegation delivered a petition with 50,000 signatures in Athens Thursday, to a U.N. envoy at a week-long U.N.-sponsored forum on Internet governance. The signatures appeared under a statement reading: "I believe the Internet should be a force for political freedom, not repression."

More than 1,000 Internet experts from 30 countries participated in the four-day summit, which considered the future of the Internet.

The forum, which ended Thursday, was mandated by a huge U.N. technology summit last year in Tunisia.

Earlier this week, Amnesty and other forum participants accused major U.S.-based technology firms of colluding with the Chinese government to censor the Internet. Activists accused leading tech firms, including Google, Microsoft and Yahoo, of selling technology to Beijing that helps police there crack down on human rights activists.

The tech firms flatly denied the charges, saying they are not colluding with anyone. A Microsoft spokesman said Chinese authorities would probably expel any foreign technology companies that refused requests from police for help in identifying Internet users.